Yes you are right this has been set to a a max of 100. How many iterations do you need ? . You could split it into multiple rows of 100 iterations each or execute the workflow multiple times to set volume options in batches of 100
Unfortunately we don't have a way to do this now. The limit was added to protect the server from being stretched beyond capacity. I am taking this down as a feature request. The only way you can do it now is to either somehow chunk them into 10 rows of 100 volumes or execute the workflow multiple(10) times with sufficient time duration between executions to allow the DFM servers and WFA to see the updated volumes.